Economic Importance of Catalysts

The modem industrialized world would be inconceivable without catalysts. There is no other technical principle which combines economic and ecological values as closely as catalysis. The development of chemical products iu advanced, industrialized societies will only be technically, economically and ecologically possible by means of specific catalysts. Examples include the specific production of stereochemicaUy pme pharmaceuticals, the constraction of tailored polymer materials, the reduction of pollutants from manufacturing plants and combustions systems (e.g. power stations, motor vehicles). Another major topic for the 21 century, the production, storage, and conversion of energy, will also be promoted by catalysts [4]. 

Approximately 80% of all catal54ic processes require heterogeneous catalysts, 15% homogeneous catalysts and 5 % biocatalysts [3]. The total commercial value of all catalysts worldwide is over 12 billion EUR. In crude oil refining processes the catalysts costs amount to only about 0.1% of the product value, and for petrochemicals this value is about 0.22%. 

Since the special properties of the catalysts decisively influence the economics of a process, their true economic importance is considerably higher than their. qnarket value . The value of the products that are produced with catalysts is 500 billion EUR p.a. Also market estimates vary widely - for example, there are no figures available for the considerable internal consumption of the chemical industry - the key importance of industrial catalysts can be recognized from the above data. In this chapter we shall treat the catalysts according to their area of use. 

The traditional area in which catalysts have been used for over 100 years is the chemical industry. For example, the contact process for the production of sulfuric acid was introduced as early as 1880. In the 1920s and 1930s catalysts for crude oil processing came on the market, initially in the USA and later in Europe, mainly after World War II. Environmental catalysts became of importance from 1970 on- 

Industrial Catalysis A Practical Approach, Second Edition, Jens Hagen Copyright 2006 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 3-527-31144-0 

---

In spite of the economic importance of catalyst deactivation, a very small percentage of the publications in catalysis are formally devoted to this subject. Hegedus and McCabe reported that, in the period 1967-1978, less than 1% of the publications in catalysis were devoted to deactivation. In the following years, the percentage increased but is still very small. The percentage of publications concerned with the regeneration of the catalytic activity is even smaller. The Catalyst Deactivation Symposia have proved crucial to the advancement of knowledge in this subject. The first one was held in Antwerp in 1980 and the fifth will be held in Evanston in June 1991. 

Heterogeneous catalysis is widely used in the chemical industry to produce thousands of different products in massive amounts. On a global scale, the technological and economic importance of heterogeneous catalysis is immense because it provides the backbone of the world s chemical and oil industries. This is the reason for intense research in both academic and industrial laboratories. Depending on the particular compounds to be synthesized, the chemical active constituents of a catalysts can be metals ". ... 

The major application significance, and resulting economic importance, of the polyolefins were not completely satisfactory. The main characteristics of this material included a molar mass distribution that was very wide, in addition to which its tacticity was not uniform. These aspects affected its properties and processing and restricted its applicability. The cause of these difficulties lay in the fact that the Z/N catalysts comprised solid bodies on whose surface large numbers of chains grew at varying rates, resulting in wide molar mass distribution. 

The carbonylation of olefins, by using such strong acids such as H2SO4, H3PO4-BF3, or HF-SbFs (superacids or magic acids) as catalysts, is known as the Koch synthesis. It 3delds predominantly branched isomers of carboxylic acids Neo acids (Exxon) and Versatic acids (Shell). The economic importance of these products is far less than that of the compovmds obtained by Reppe reactions (85,86). 

Over the last 40 years the economic importance of industrial aldehyde production has led chemists and engineers to propose new and alternative ways to further optimize hydroformylation technologies. Particular attention in these attempts was always given to new concepts by which to combine the molecular defined, homogeneous nature of hydroformylation catalysis with cleverer ways to separate products and catalyst after reaction. Many of the reported strategies have focused on the... 

The choice of catalyst is based primarily on economic effects and product purity requirements. More recentiy, the handling of waste associated with the choice of catalyst has become an important factor in the economic evaluation. Catalysts that produce less waste and more easily handled waste by-products are strongly preferred by alkylphenol producers. Some commonly used catalysts are sulfuric acid, boron trifluoride, aluminum phenoxide, methanesulfonic acid, toluene—xylene sulfonic acid, cationic-exchange resin, acidic clays, and modified zeoHtes. 

The ageing and decay characteristics of catalysts are of immense importance in defining the economics of processes. The simplest criterion that can be applied is that of total productivity during the life of the catalyst and also loss of productivity during the shut down required for catalyst replacement. Figure 2 illustrates notional performances for two catalysts A and B in hypothetical processes in which productivity is simply a measure of quantity of product produced. Catalyst A has a lower initial productivity but is more stable in use and dies off at a much lower rate than catalyst B, which has a high initial productivity which falls relatively... 

The selection of reactor type in the traditionally continuous bulk chemicals industry has always been dominated by considering the number and type of phases present, the relative importance of transport processes (both heat and mass transfer) and reaction kinetics plus the reaction network relating to required and undesired reactions and any aspects of catalyst deactivation. The opportunity for economic... 

Although the major use of aluminum by far is as a metal, some aluminum compounds also are economically important. Foremost among these is aluminum chloride, which is an important industrial catalyst. 

For the elimination of NOx in the exhaust gases of gasoline motors, more and more effort has been devoted to the elaboration of new catalysts, potential substitutes of Pt-Rh based solids Indeed, with such materials, the Rh/Pt ratio is higher than in the Pt-mine It is economically important, therefore, to elaborate new catalysts either without Rh or with a lower amount of Rh than the catalysts of the present day. 

Development of value-added products from glycerol can help the total economics of an oilseed biorefinery. Propylene glycol is one such product. This chapter will present the development of catalysts that can convert glycerol to propylene glycol in high yields. Our work has focused on a class of catalysts based on Re, which as a cometal imparts important character to the catalysts. 

---